烃分子结构与在FAU和MFI分子筛中扩散特性的定量关系

Quantitative Relationships Between Molecular Structure and Diffusion Characteristics of Hydrocarbons in FAU and MFI Zeolites

采用分子模拟方法系统研究了不同尺寸的烷烃、芳烃、环烷烃分子在FAU和MFI分子筛中的扩散特性,计算了一系列反映分子微观特征的结构参数,建立了烃分子结构参数与扩散特性间的定量关系。结果表明,进入定量关系表达式的主要是与分子空间占有情况相关的参数,如分子的三维尺寸、最小截面积、转动惯量等。由于烷烃、芳烃、环烷烃分子具有不同的结构特征,因此进入各自表达式的参数不同。建立的定量关系意义明确、相关性好、预测性能强。由定量关系可找到影响烃分子扩散特性的结构参数,为预测烃分子的扩散特性提供了一种简单、快捷的方法。

The diffusion characteristics of alkanes, aromatics and cycloalkanes with different sizes in FAU and MFI zeolites were investigated by molecular simulation method. The molecular structure parameters which reflected the microscopic characteristics were calculated. And the quantitative relationships between molecular structure parameters and diffusion characteristics were established. The parameters filtered into the quantitative relationships were related to the molecular space occupancy, such as three dimensional dimensions, the minimum cross-sectional area, inertia moment. Because alkanes, aromatics and eycloalkanes had different structure characteristics, the parameters filtered into the relationships were different. The established relationships had clear physical meanings, good correlations and predictive abilities. According to the quantitative relationships, the molecular structure parameters which affect the diffusion characteristics could be found, and the diffusion characteristic of a given hydrocarbon could be predicted quickly.